1. Field of the Invention
This invention relates to dental implements, and more particularly, to novel dental impression trays that are mechanically adjustable to accommodate various mouth sizes in order to obtain an accurate impression of the upper and/or lower dentition of a patient.
2. The Background Art
With regards to dentistry, an impression is often used to create an imprint or negative likeness of the teeth and adjacent portions of the jaw (e.g., tooth formations, the contour of the gums, etc.) preparatory to dental repair, orthodontics and restoration of missing dental structures. Impressions are typically made by placing a soft, semi-fluid material within the confines of an open trough or channel of an arcuate tray which is then positioned within the mouth of a patient, thus allowing the material to set or cure. Depending upon the material used, the set impression may be either hard or have some elastic characteristics.
To provide the most accurate articulation, the impression cast should generally represent the entire dental arch. In this regard, the impression cast can be used to establish inter-proximal contacts, buccal and lingual contours and occlusion with the opposing teeth. From the negative or female cast of the teeth and surrounding structures, a positive reproduction or male cast may be created for the purpose of fabricating inlays, crowns, bridge retainers, dentures, restorations or the like.
Traditionally, before an impression cast of the dentition is created, a stock tray is selected by the dentist or dental assistant that will generally fit the dental arch of the particular patient. Since the dental arch may differ widely from patient to patient, various sizes of impression trays (e.g., small, medium and large) were developed by those skilled in the art to accommodate various mouth sizes, bite radii of teeth and to correspond to upper and lower anterior or quadrant impression sites.
For example, those skilled in the art developed prior art dental impression trays formed of metal, such as stainless steel, and having a pair of spaced-apart vertical walls joined by a semi-rigid mesh material disposed horizontally between the opposing vertical walls. Extending outwardly in structural relation to at least a portion of the surface facing of one of the vertical walls, a handle member may be provided to facilitate a means for gripping the impression tray for purposes of manual manipulation. In addition, an open trough or channel is generally formed between the opposing vertical walls, wherein the horizontally disposed mesh material provides a porous surface flooring for the trough. In operation, the mesh material provides a means for permitting excess flow of impression material to become displaced and extruded there through. Dental impression trays of the prior art may further include openings formed in the vertical walls of the trough or channel which generally function as an anchoring surface for the impression, thus allowing the excess flow of impression material to become attached thereto.
Although seemingly useful for their intended purposes, there are several practical disadvantages of prior art dental impression trays comprised of metal. For example, a significant disadvantage of prior art metal impression trays includes the difficulty associated with maintaining proper cleaning and sanitation of the impression trays using heat or chemical sterilization methods or techniques to avoid cross-contamination in order to be able to reuse the various sized stock metal impression trays from patient to patient.
Attempting to alleviate some of the disadvantages associated with the amount of time and energy expended to maintain proper sanitation of prior art metal impression trays, in addition to the costs associated therewith, disposable impression trays were developed by those skilled in the art. As noted above, since the dental arch may differ widely from patient to patient, various sizes of disposable impression trays (e.g., small, medium, and large) were developed to accommodate various mouth sizes, bite radii of teeth, and to correspond to upper and lower anterior or quadrant impression sites.
In accordance with other such prior art apparatus and techniques for making an impression cast of the upper and/or lower dentition of a patient, those skilled in the art developed adjustable impression trays. For example, an adjustable impression tray of the prior art may comprise a primary impression unit and a movable extension unit telescopically mounted on the primary unit for adjustable relative thereto. The primary unit being provided with primary leg portions having secondary leg portions extending therefrom, wherein the primary leg portions include a first flap means extending outwardly therefrom and over the secondary leg portions. In operation, the secondary leg portions comprise a tab means cooperative with the first flap means of the primary leg portions so as to facilitate the first flap means being movable relative to the tab means. The movable extension unit further comprising a second flap means having a series of slots therein for registry with the tab means of the secondary leg portions for fixation in relation to the primary leg portions of the impression tray.
Another example of prior art adjustable impression trays includes a main arcuate portion with parallel spaced vertical walls having extension portions slidably disposed in frictional engagement therewith for lengthwise adjustment in relation to the main arcuate portion. The engagement means between the extension portions and the main arcuate portion of the impression tray may include T-shaped rails formed in the outer faces of the opposing walls and corresponding recesses formed in the inner faces of the respective walls of the extension portions. Similarly, annular recesses may be formed in the outer faces of the opposing walls and corresponding annular nibs may be formed in the inner faces of the respective walls of the extension portions to provide a slidable engagement there between.
A meaningful disadvantage with prior art adjustable impression trays of the general type disclosed herein is that they only provide means for accommodating a structural adjustment in the dimensional length of the channel. In this regard, because these prior art adjustable impression trays fail to provide for any adjustment in the dimensional width associated with various sizes of the dental arch, they are generally limited in their particular utilization.
In an effort to accommodate an adjustment in the dimensional width of a dental impression tray, those skilled in the art developed heat-expansive impression trays which may be formed of a thermoplastic material which is malleable at elevated temperatures so that the impression tray can be generally shaped and configured in such a manner so as to accommodate the corresponding dental arch of a particular patient. For example, prior art heat-expansive impression trays may structurally comprise an elongated channel including a buccal side, a lingual side, and an occlusal side. The occlusal side of the channel including an outwardly extending folded section which may be fully or partially unfolded when the channel is heated, thereby providing a means for expanding the dimensional width of the elongated channel. Two additional folded sections formed in opposed posterior portions of the impression tray may also be provided which, when heated at a specific softening temperature, can be partially or fully unfolded by pulling the posterior ends of the tray away from the anterior portion of the same, thus extending the dimensional length of the elongated channel.
While prior art adjustable and heat-expansive impression trays may appear generally suitable for their intended purposes, these prior art impression trays nevertheless leave much to be desired from the standpoint of effectiveness of operation, manufacturing costs, simplicity of construction in relation to a multiplicity of parts, and functionality as to universal application. As will be appreciated in this particular art, economic considerations are significant when dealing with the highly competitive dental industry, since multiple stock impression trays (e.g., small, medium, and large) or complicated devices are frequently found to be commercially impractical. Accordingly, even a slight savings in cost may substantially enhance the commercial appeal of a particular component or assembly when considering issues of mass production of the product.
In accordance therewith, it would be desirable to provide an adjustable dental impression tray which realizes the advantages of the prior art devices while at the same time eliminates the disadvantages associated therewith. Such an adjustable dental impression tray is disclosed and claimed herein.
In view of the foregoing, it is a primary object of the present invention to provide novel dental impression trays which may be mechanically adjusted to accommodate various mouth sizes, bite radii of teeth, and to correspond to upper, lower, anterior, quadrant, or triple bite impression sites.
It is also an object of the present invention to provide an adjustable dental impression tray which is formed of a disposable material, thus avoiding the disadvantages associated with having to clean and sanitize metal impression trays.
It is further an object of the present invention to provide an adjustable dental impression tray which may be adjusted to the specific size of the patient""s mouth, thereby eliminating the need for a dentist to stock various sizes of impression trays (e.g., small, medium, and large) in order to accommodate different dental arch configurations.
Additionally, it is an object of the present invention to provide an adjustable dental impression tray which increases the accuracy of the impression cast, while decreasing dental chair time.
Similarly, it is an object of the present invention to provide an adjustable dental impression tray which reduces the possibility of deformation of the impression cast.
It is a further object of the present invention to provide an adjustable dental impression tray which simple in construction, effective in operation, and inexpensive to manufacture.
Consistent with the foregoing objects, and in accordance with the invention as embodied and broadly described herein, an adjustable dental impression tray includes a first arcuate member having a distal end and a proximal end. A second arcuate member having a distal end and a proximal end is preferably movable connected to the first arcuate member adjacent the proximal end of each arcuate member. Each arcuate member is adapted to receive a quantity of impression material. A handle may be attached to one of the arcuate members to facilitate easy removal of the dental impression tray with minimal deformation of the impression material.
The dental impression tray of the present invention preferably includes an adjustment mechanism for selectively fixing the position of the first arcuate member relative to the second arcuate member. The adjustment mechanism may include the first arcuate member having an opening, and a second arcuate member having a fastener member corresponding to the opening in the first arcuate member. In one presently preferred embodiment, the fastener member includes a post configured within the proximal end of the first arcuate member with the opening positioned within the proximal end of the second arcuate member. The post and opening may be configured for movable mating engagement with each other, thereby permitting the first and second arcuate members to be selectively positioned relative to each other. In another presently preferred embodiment, the adjustment mechanism includes concentric gears with a spring-loaded button device for releasing the gears and allowing the arcuate membersto move relative to each other. When the button is disengaged, the concentric gears realign preventing further movement. Thus, the dental impression tray of the present invention is pivotally adjustable through a range of motion allowing one tray to closely and comfortably fit a wide variety of dentition sizes.
The first and second arcuate walls include an outer wall. In one presently preferred embodiment, the first and second arcuate members each include a frame member attached to and spread apart from the outer wall. A membrane may extend between the frame member and a centerline portion of the outer wall of each arcuate member, along the length of the outer wall, thus providing a surface upon which the impression material may be placed. Thus, an upper and lower tray portion are simultaneously created within the adjustable dental tray which allows a mold to be taken of the upper and lower dentition simultaneously. This xe2x80x9ctriple bitexe2x80x9d configuration allows the user to not only create an impression of the upper and lower dentition, but allows the user to create a mold which shows the bite relationship between the two.
The first and second arcuate members are configured such that a portion of the first arcuate member can be positioned to closely overlap a portion of the second arcuated member, forming an overlap portion. The first and second arcuate members may be configured such that the first and second arcuate members can be positioned relative to each other to form a substantially U-shaped channel between the outer walls of the first and second arcuate members and a perimeter of the overlap portion. This channel approximates the curvature of a person""s dentition.
In another presently preferred embodiment, the first and second arcuate members each include an inner wall spaced apart from the outer wall which, together with the membrane extending there between, form a generally U-shaped channel approximating the curvature of a person""s dentition.
The outer wall of at least one of the arcuate members may include a notch adjacent the proximal end of the arcuate member which permits the user to break arcuate member at the notch. This notch allows the user to create a xe2x80x9cquadrantxe2x80x9d dental tray for taking an impression of the upper or lower left or right portions of the patient""s dentition, by breaking off the appropriate arcuate member at the notch. The outer wall of the arcuate members may also include a notch positioned adjacent a middle portion of each arcuate member between the distal and proximal ends. This notch allows the user to break the arcuate members to create an xe2x80x9canteriorxe2x80x9d dental tray for taking a dental impression of the front portion of the patient""s upper or lower dentition.
In another presently preferred embodiment, at lease one of the arcuate members includes a locking member for retaining the impression material. The locking member may include a flange member which extends along a portion of one of the arcuate members. In another presently preferred embodiment, the locking member may include vents configured within at least one of the arcuate members which allows a portion of the impression material to flow through the vents and anchor itself to arcuate member.